My question is about the very definition of vulnerability and its negative connotations.

I don't mean to split hairs about semantics but I find it hard to open myself up to this concept fully when at the very root it seems that the word by her definition is being reclaimed and redefined. Brene Brown says, "Vulnerability is simply defined as uncertainty, risk, and emotional exposure." (http://www.fastcompany.com/3001319/why-doing-awesome-work-means-making-yourself-vulnerable) This isn't quite the definition set forth by dictionary standards:

Definition of VULNERABLE (Merriam-Webster)
1: capable of being physically or emotionally wounded
2: open to attack or damage : assailable
3: liable to increased penalties but entitled to increased bonuses after winning a game in contract bridge

Apr 4 2013:
I think Ms. Brown's point is that we need to be careful about expecting to always have 100% confidence that we are not in any danger of being wrong. We should not be reluctant to proceed in the face of uncertainty. We cannot always, indeed we can never, know everything. We must be willing to press-on in the face of potential wounds, attacks, and damage-- all the characteristics of vulnerability.

Apr 6 2013:
Seems to me the two definitions basically agree. The first definition says uncertainty and risk, and the second says open to attack. When you are open to attack, you are experiencing uncertainty and risk.

Apr 5 2013:
Love and trust are important in human relationships. Both require a certain level of vulnerability, a certain level of risk.
Vulnerability could be easily understood as defined; maybe harder to accept.
We dont know everything about the people we love or trust, we cant. What if the pilot of the plane you just boarded is going through a nasty divorce and has just downed a sack of pills with a bottle of Jack Daniels? What if the waiter in your favourite restaurant is a psycho and decides to put some cyanide in your food? What if that woman you are crazy about does not love you one bit and is just using you as a reference personality for a novel she's working on?

Life is what it is; you have to trust somebody. It may seem to put you in a position of weakness; but believing the worst in all humanity is a far far miserable and pitiful state of weakness.

Apr 7 2013:
Bonnie,
I don't perceive vulnerability as negative or positive. It is a state of "feeling", or "being", which can be very subjective, depending on the individual.

Could it be that you are seperating different part of the meaning of vulnerable, rather than perceiving them as all part of the whole?

1. "Vulnerability is simply defined as uncertainty, risk, and emotional exposure"
2. "capable of being physically or emotionally wounded; open to attack or damage; liable to increased penalties but entitled to increased bonuses...."

Together:
The feeling of vulnerability includes uncertainty and emotional exposure. When we take this risk, there is often the possibility of being physically or emotionally wounded, open to attack or damage. We may be exposed to increased penalties, AND/OR increased bonuses.

How, why, when, where and with whom we allow ourselves to be vulnerable, often depends on our feeling about our "self". I suggest that it may feel like a negative if we are less secure in ourselves. Sometimes, when people are not clear in themselves, they are unaware of the risk with allowing themselves to be vulnerable. When we know our "self", we may weigh ALL factors and be more clear regarding the risk, consequences and benefits.

Apr 5 2013:
It is the Ego that is Vulnerable. A Misidentification with the Ego (believing You are Actually the Ego) is what prevents the Opening Up. The vast majority of us suffer from this misunderstanding :-) But that is changing rapidly.

I don't personally see vulnerability as being altogether a negative connotation, to get from (a) to (b) I need to get in my car & make myself vulnerable to other drivers & them to me but all I see is for me to get from (a) to (b). In every moment in one's life we are vulnerable however life isn’t seen like that even though we are always vulnerable to it in one way or another.

However if my mode of thought is negative vulnerability takes on a negative connotation as you said, it really depends on your mode of thought if vulnerability is going to be negative or not.